<![CDATA[Biodiesel were produced by trans-etherification of castor oil with alcohol in the presence of NaOH catalyst. Thereaction mechanism and model of castor oil trans-etherification isA + 3B C + 3 DA, B, C, and D were castor oil, alcohol, glycerol, and ester. The reaction rate equation was r=-dCA/dt =k1(CA)(CB)3–k2(CC)(CD)3. In this study was used two measurement method of free fat acid as the rest content ofcastor oil with SNI 01-3555-1998 and AOAC (Association of Analytical Chemist). It found that SNI 01-3555-1998 method was the easier and the acurate measurement. The classification of alcohol used was methanol andethanol to compare the action both of them. Methanol produces the higher conversion than ethanol. The reactionin a batch reactor with temperature 40, 50, and 60°C in atmospheric pressure as the operation condition tolooking for kinetics parameter of trans-etherification. Coefficient reaction rate and activation energy were lookinto kinetics study. Reaction rate was a mathematics model as a function of concentration and time which solvedby Runge-Kutta, multivariable optimization and SSE (some square error) method using Matlab. The activationenergy (Ea) and impact factor (A) obtained by linier regression method. The result of study obtained the kineticsparameter of trans-etherification with methanol k1=1.9313x1031exp (-41.940/RT) average error 0.0010 andk2=2.7678x1025exp(-37.362/ RT) average error 0.0003. While kinetics parameter of trans-etherification withethanol obtained k1=1.168x1019exp(-24.588/ RT) average error 0.0306 and k2=4.9966x106exp(-10.328/RT)average error 0.1589. It means, more reactive alcohol then bigger the value of kinetics parameter.]]>
